Chapter 23 Reading guide
1. what is the smallest unit of evolution and why is this important to understand? The population is the smallest unit of evolution . This is important to understand because it keeps clear what is evolving. 2. Define the following terms:
a. Microevolution: evolutionary change below the species level; change in the genetic makeup of a population from generation to generation. It is evolutionary change on its smallest scale b. Population: a localized group of individuals that belong to the same biological species, capable of interbreeding and producing viable offspring. c. Population genetics: the study of how populations change genetically over time. d. Gene pool: the total aggregate of genes in a population at any one time. It consists of all alleles at all gene loci in all individuals of the population 3. What is the Hardy-Weinberg Theorem and why does it appear to be an apparent contradiction to evolution? The theorem states that frequencies of alleles and genotypes will stay the same as long as the gametes are contributed to the next population at random. This appears to be a contradiction to evolution because it seems to say populations will never change. However, this condition only exists under certain conditions which do not apply to the majority of populations. The five conditions are: 1. Extremely large population size. 2. No gene flow. 3. No mutations. 4. Random Mating 5. No natural selection. 4. What is Hardy-Weinberg equilibrium? Hardy-Weinberg equilibrium is the condition describing a non-evolving population (one that is in genetic equilibrium). 5. Use the blank diagram below to relate the H-W equation to a Punnett square. The theorem states that frequencies of alleles and genotypes will stay the same as long as the gametes are contributed to the next population at random. This appears to be a contradiction to evolution because it seems to say populations will never change. However, this condition only exists under certain conditions which do not apply to the majority of populations. The five conditions are: 1. Extremely large population size. 2. No gene flow. 3. No mutations. 4. Random Mating 5. No natural selection.
6. What are the five conditions for H-W equilibrium to maintained? Extremely large population size ,No gene flow, No mutations, Random mating, No natural selection 7. How can the H-W equation be used to today in terms of human health? The Hardy-Weinburg equation can be used to estimate percentages of humans that carry alleles which lead to inheritable diseases. If you have the percentage of people with a disease and if you know weather the disease is recessive than it is easy to find the percentage of a population that are carriers of the disease. With this information one can predict how the disease will affect a population in the future. 8. What are the two broad processes that make evolution possible? The two broad processes that make evolution possible are mutation and sexual recombination. 9. What is the impact of the following:
a. Point mutation: Has impact in phenotype, like a sickle cell disease, most however are harmless. A reason for this is that much DNA in eukaryotic genomes do not code for protein products. Because the genetic code is redundant, point mutations in genes may have little effect because they do not alter proteins amino acids. It is a change in one base in a gene. b. Gene duplication Duplications, deletion and rearrangement of chromosome segments are almost always harmful but if it leaves that gene intact it may be neutral and in rare cases beneficial. DNA is introduced to a new genome through activity of transposable elements. If the duplicated segment does not have a negative effect it can continue over generations providing an expanded genome that may take on new function. New genes may also come to be when the coding portion of a gene or exon is shuffled within the genome. c. Sexual Recombination Sexual...